Railway switch operating apparatus



Dec. 30, 1958 Filed June 22, 1955 c. PAOLINO, JR EIAL 2,866,612

RAILWAY SWITCH OPERATING APPARATUS 4 Sheets-Sheet 1 INVENTORS Charles Paolino Jr. and Robert A Wenston THEIR ATTORNEY Dec. 30, 1958 c, PAQLINO, JR ETAL 2,866,612

RAILWAY SWITCH OPERATING APPARATUS 4 Sheets-Sheet 2 Filed June 22, 1955 QNS N Dec. 30, 1958 c, PAQLINO, JR r 2,866,612

RAILWAY SWITCH OPERATING APPARATUS Filed June 22, 1955 4 Sheets-Sheet 5 5; Vaas 59 54a 30a llls'ulaziozi ovemen Flii Plessurq Source F y Uharl and Robert A. Wenszforl w. A W:

THEIR IQZTORNE'Y Dec. 30, 1958 c. PAOLINO, JR r AL 2,866,612 RAILWAY sw'rrcn OPERATING APPARATUS 4 Sheets-Sheet 4 Filed June 22, 1955 d mm m w m fimwv @w m T ww A g PAL. m @w 3w m ab w mm aw mm @v u QB MN a Ev N N \w @m 2,866,612 RAILWAY SWITCH OPERATING APPARATUS Charles Paulina, In, Penn Township, and Robert A. Wenston, Pittsburgh, Pa., assignors to Westinghouse Air Brake Company, Wilmerding, Pa, a corporation of Pennsylvania Application June 22, 1955, Serial No. 517,286

' 6 Claims. c1. 246-258) Our invention relates to railway switch operating apparatus, and particularly to an air shut-off valve for an electropneumatic switch operating apparatus having manual means for operating the apparatus.

Electropneumatic switch movements are provided with a piston and cylinder assembly for moving the switch points of a railway switch to their normal and reverse positions, the cylinder being connected to a suitable source of air supply through electromagnetically controlled air valves. The operating windings of the valve actuating magnets are connected into control circuits whereby the electromagnets may be selectively energized to control the operation of the switch. One such switch movement is described and illustrated in Letters Patent of the United States No. 2,092,828 issued on September 14, 1937, to Herbert L. Bone for Railway Switch Operating Apparatus.

In the particular switch movement described in the aforesaid patent, the switch points of a railroad switch may be moved by means of a hand-throw lever. The arrangement of the hand-throw lever is such that a clutch or disconnect device between the hand-throw lever and the hand-throw shaft of the movement prevents any force from being transmitted to the hand-throw lever when the operating shaft is rotated by the fluid pressure motor.

A latch mechanism is provided for the hand-throw lever whereby the lever is latched and locked in its normal position. The latch mechanism is provided with a safety interlock whereby upon release of the latch mechanism to free the hand-throw lever, electrical contacts, in series with the electromagnets operating the control valves, are opened to prevent power operation of the movement during manual operation. It has been found in electropneumatic switch movements of the character illustrated in the aforesaid patent that, with the movement conditioned for manual operation by the hand-throw lever, the switch movement may be power operated by manual operation of the valve magnets, thus supplying fluid pressure to the cylinder. With the hand-throw lever exposed and the hand-throw lever clutch device damaged either through maliciousness or carelessness, the hand-throw lever may be rotated upon manual operation of the control valve magnets.

It is therefore an object of our present invention to provide a safety shut-off valve in the supply line connecting the operating cylinder of an electropneumatic switch movement to a source of fluid pressure whereby the pressure source is cut off when the switch movement is conditioned for manual operation.

Another object of our invention is to provide a latching mechanism for the hand-throw lever of an electropneumatic switch movement which latches and holds the hand-throw lever in one extreme position and which upon being released operates the shut-off valve in the fluid supply line to close the valve.

Still another object of this invention is to provide a locking member or bar for the hand-throw lever latch- 2 ing mechanism of an electropneumatic switch movement whereby the latching mechanism is held in its tripped or unlatched position as long as the hand-throw lever is in any positionother than its normal position.

In carrying out our invention we provide a valve housing secured to the lever latch stand of an electropneumatic switch movement similar inmost respects to the switch movement disclosed in the aforesaid Bone patent, the valve'housing being provided with a centrally dis-, posed tapered opening for receiving a tapered valve cock rotatable between two extreme positions. The valve housing is provided with three openings terminating in the tapered opening, the three openings being'connected respectively to atmosphere, to a source of fluid pressure, and by a flexible conduit to the switch movement. The tapered'valve cock is formed with a groove in its periphery which is adapted upon rotation of the valve cock to connect the air supply opening with the opening connected by the conduit to the movement in one extreme or normal position of the valve cock, and to connect the movement opening with the atmosphere opening in the other extreme or reverse position of the valve cock. In releasing the latch member to free the handthrow lever of the switch movement, the valve cock herein provided is rotated through a suitable connection with the latch member shaft to cut off the pressure supply to the switch movement valve mechanism and vent the valve mechanism to atmosphere.

Fig. 1 is a top plan view of a typical railroad switch,

layout provided with an electropneumatic switch movement embodying our invention.

Fig. 2 is a front 'elevational view of the switch movement illustrated in Fig. 1.

Fig. 3 is a top plan view of the switch movement with the cover removed and portions of the movement shown in section for illustrating to better advantage certain of the elements.

Fig. 4 is an enlarged front elevational view of the latching mechanism and shut-off valve embodying our invention, portions thereof being broken away and shown in section.

Fig. 5 is a sectional view taken approximately along the line VV of Fig. 4.

Fig. 6 is a sectional view taken approximately along the line VTVI of Fig. 4.

Fig. 7 is a side elevational view of the switch move-. ment illustrated in Fig. 1.. r

Fig. 8 is an enlarged view of a detail'of the hand crankshaft, while Fig. 9 is a sectional view taken along the line IX -IX of Fig. 3.

Referring now to Fig. 1 of the drawings, the reference numeral 1 designates a railway switch compris-- ing two fixed rails 2 and 3 and two movable railsor switch points 4 and 5. The fixed rails 2 and 3 are laid on tie plates 6 and are secured to the ties 7 in the usual To preventv the return of the latching member to its latched position after the hand-throw lever has been rotated to its reverse position, we provide a locking member or bar manner. The switch points 4' and 5 are secured together by a tidr'b'cf 8 and maybemovednbmmenormal position illustrated to a reverse position in which the switch point 4 abuts the fixed rail 2-and back tothe normal positiontbymeans'ofa throwrod9' connected'to the tie rod by the'usualswitch b'a'sket ltl.

A railway switch operating vmechanism 11 similar in rriost' respects tothe mechanism illustrated and-described in the aforesaid Bone patent is secured in the usual inannerto the ties'7 adjacent to the switchl for movingthe switch points 4 and 5 to theirnorrhal and reverse positions. The switch operating mechanism ll'is enclosed in a suitablejcasing 12havihg' a'hinged'cove'r 13L Mounted within the casing 12' adjacent the right-hand end, as

viewed inFigs; 3 and 7, isa' trahsver'sely disposed crankshaft 1'4, thefshaft' being seciir'ed in' suitable bushings 15 fastened: in theisideso'f the casing 12, .Rotatably mounted" on the ciankshafh 14, asibybearings 16, is a cylindrical'roeker shaft 117i Secured to the rocker shaft- 17 is a switch operating crahk18 comprising. a pair of laterally'spa'cedarmsf18a and 18b, and a toggle crank arm 19, thec'r'ai k 18'a'nd-the crank'arm 19 being angula'rly disposed relative to each other-to form'a 'bellcrank member (Figi 7,). v r

The rocker shaft" 17 is adaptedto be rotated from one extreme or normal position to anotherextremeor reverse position by the coaction of a' fluid pressure motor 20and'a toggle arrangement generally designated by the reference numeral 21. The fluidpressu're motor 20 comprises a cylinder 22 closed at oneen'di'by a cylinder head 23 and provided a'tthe other end with a stuflfing box 24 through which'a' piston rod 25 eiitends'into' the cylinder. The free end of the piston rod is' pivoted on a crank pin 26 secured in the ends of the switch operating crank arms 18a and 185; A spacer 27, on the crank pin 26 is interposed between: the pivoted end of the piston rod and the crank arm l'8ato position the pistonrod relative to the crank arms, the free endo'fthe throw rod 9 connected to the tie rod 8, of the switeh 1 being pivoted, onthe crank pin 26 between the piston rbd and theciank arm 18b.

The innerend of the tpistonrodl s is secured to a reciproc'able piston 28 withinthe cylinder 22. The, cylinder head 23 is pivotally mounted on a transversely extending rod 29 adjacent the, left-hand end of casing 12 as viewed in Figs. 3 and, 7. Integral with the cylinder head 23 isa' valve mechanism3(l'corfiprising two valve magnets 31a and 31b for controlling the operation of two valves 32d and32b', respectively. Themagnet 31a and valve 32a will hereinafte'nb'e referred to as the normal magnet and valve, whilethe'tniag'ri'et' ftlb and valve' 32b will be referred to as'the reverse magnet and valve. The valve mechanism is ess'entia'llythe same as that illustrated and described in Letters Patent of, the United States No. 1,875,853 granted to John P; Coleman on September 6, 1933 for Railway Trafiic Controlling Apparatus, and in the aforesaid Bone patent; A detailed description of the valve mechanism 30 is believed unnecessaryforthe purposes of the present application, except tostate that, when the" normal valve magnet 31a is energized, fluid pressure will .be-admitted to the righthand end of cylinder 22, (Fig; 7) causing the piston 28 to be moved toward the left-handend of its stroke, while energization of the reverse valve magnet 31b will permit fluid pressure to enter the left-hand end of the cylinder to' move the cylinder toward the right-hand end of the stroke. As will hereinafter-be more fully described, fluid pressure/for the" cylinder 22 is supplied through a conduit 33 connected to .the valve mechanism by a suitable The switchoperating rocker shaft 17 is biased'to its normal extreme position as illustrated in Figs. 3 and 7 by the toggle mechanisin- 2'1 'l he toggle mechanism comprises" a spring retainer sleeve 36 which" is slida'oly mounted on the end o'f a spring rod 37. The sleeve 36 is provided"with an annular flange 36a through which the end of the spring rod extends, the end of the spring rod being threaded and carries a nut 38 which c'o'acts with the sleeve flange to limit the relative longitudinal movement of the sleeve in the one direction. The nut is preferably hexagonal, while the sleeve opening is of a similar contour so that relative rotation of the sleeve and nut is prevented. A spring retainer 39 is secured to the other end of the spring rod, and a coilspring 4G is interposed between the spring retainer 39 and a spring retainer flange 36b formed on the sleeve. The one end of the spring rod 37 is pivotally m'ountedon therod 29 while the other end is pivotally mounted to the toggle crank arm 19 of the rocker shaft by a pin 41 which passes through an eye 19a of the crank arm and through suitable openings provided inthe bifiurcated extensions 36c formed on the end of the spring rod. The parts are so proportioned that the toggle mechanism will occupy its dead center position when the switch operating rocker shaft is in its' mid-stroke position.

Briefly-stated, the switchoperating mechanism thus'far described will move the switch points from their normal position as illustratedin Fig. l to their reverse position upon energization of the reverse valve magnet 31b. The reverse valve 32b will thus' be operated to permit the fluid pressure to move the cylinder to the right to rotate the rocker shaft 17 in a'counterclockwise direction (Fig. 7). The toggle spring will be compressed by the counterclockwise rotation of the crank arm 19 on the rocker shaft until the rocker shaft moves'past its midstroke position. The toggle mechanism 21 then being past its dead center positionwill take over and aid the motor 20 in moving the rocker shaft to its reverse position, thereby moving'the' switch points to their reverse position. The switch points may be returneduponenergization of the normal valve magnet 31a, thereby moving the motor piston 28 to the left to rotate the rocker shaft in a clockwise direction, the toggle mechanism 21 aiding the motor 20 after the mid-stroke position of the rocker shaft has been reached.

Means are also provided for the railwayswitch operating mechanism 11 for operating the switch points manually.

To this end there is secured to'the switch operating rocker shaft 17, a segment bevel gear 42 which meshes with a bevel gear 43 secured'to one end of a handcrankshaft 44. The hand crankshaft'isrnounted adjacent'the bevel geafend in abearing 45 secure'd'in a bearing retainer 46 on the" side Wall of the casing 12. The hand crankshaft isjournaled adjacent'itsother end through a suitablejournal 47 secured to the end wall of the casing. the end of the crankshaft extending out through the casing and being provided withan enlarged portion 48 (Fig. 8). The enlarged portion of the crankshaft is formed with a cam slot 49 having two axially offset, circumferentially extending p0rtions49a and 49b intercom nected by an axially extending portion 490. The interconnected ends of the slot portions 49a and 4911 are formed with arcuate recesses 49d and 496, respectively. Rotatably and slidably' mounted on the enlarged end portion 48 of thehand crank shaft 44 is a hand-throw lever 50 having a hub 51 which receives the enlarged portionof the crankshaft (Fig. 9). Threaded inthe handthrown lever hub 51 is a pin 52, the inner end of which acts as a cam follower andcooperates with the cam slot 49 provided in the end portion 48. The'cam slot 49and the pin 52 in the hub form a disconnect or clutch device whereby the hand-throw lever is at times positively connected to thehand cranks'haft'44 to permit manual operationof the switch movement 11 and which is at other times disconnected from the-han'd crankshaft to permit power operation of the switch movement. The position thepin 52 takes" inthe portions of'the cam'slot 49 is determined by the relative angular positions of the hand-throw lever and the handcrankshaft. Cam members 53a and'53b" on the exterior ofthe hand-throwlever hub cooperate with a camming stud 54 fastened to an extending bracket 55 secured to the end wall of the casing 12 to slide the hand-thrown lever toward or away from the casing 12, to connect or disconnect the handthrow lever to the hand crankshaft as more particularly described in the aforesaid Letters Patent of the United States No. 2,092,828 issued to Herbert L. Bone. The hub 51 of the hand-throw lever is further provided with a third cam member 56 which extends approximately 180 around the periphery of the hub.

Means are provided to latch and lock the hand-throw lever 50 in its normal extreme position, and to open the energizing circuits of the valve magnets and cut off the fluid pressure supply to the valves upon release of the latching means retaining the hand-throw lever in its normal position.

To this end there is provided a lever latch 57 for locking the hand-throw lever 50 in its normal position. The lever latch comprises a handthrow lever stand 58 suitably secured to the end wall of casing 12, the stand being provided on its upper side with a jaw 59 for receiving the hand-throw lever when the lever is in its normal position. A bail 66 is provided on the outer side of the jaw 59 for locking the hand-throw lever. The stand 58 is further provided with two spaced dependent arms 61 and 62, the arm 61 being slightly longer than the arm 62 and is approximately twice its thickness. Rotatably mounted in the openings 61a and 62a provided in the respective dependent stand arms are bushing 63 and 64, the bushings being provided with square openings to accommodate a square shaft 65. The bushing 63 is welded to the square shaft 65 while the bushing 64 is fastened to the shaft by a screw 64a to facilitate assembly and disassembly. Secured to the square shaft 65 between the dependent arms 61 and 62 of the stand 58 is a hand-throw lever latching member 66 adapted when in its latched position to cover the jaw 59 of the stand to prevent removal of the hand-throw lever 50. The latch member 66 is provided with an opening or slot 66a to accommodate the bail 60 of the stand so that the hasp of a padlock (not shown) passing through the bail locks the latching member. The latching member 66 is further formed with an outwardly extending foot pedal 67 for depression to rotate the latching member to its unlocked position after the padlock has been removed. Integral with the foot pedal 67 on the underside thereof is a dependent stop 67a for abutting the arm 62 of the stand to limit rotation of the latching member. A pedal 68 forming a part of the latching member is provided to aid in returning the latching member to its latched position.

Integral with the latching member 66 is a rearwardly extending stud 69 having pivoted thereto, as on pin 70, a rod 71. The rod 71 extends through a suitable opening 12a into the casing 12, the inner end of the rod having secured thereto a contact actuating member 72 of insulating material. Secured within the casing 12 adjacent the opening 12a is a molded insulating member '73 supporting in spaced relation two electrical contact fingers 74 and 75, the contact finger 74 being the longer of the two and is secured to the actuating member 72 of the rod 71. The contact fingers 74, 75 are in the control circuit for the valve magnets 31a and 31b and are normally closed as illustrated in Fig. 6 when the lever latch 57 is in its latched position.

The novel means embodying our invention is provided to cut oil the fluid pressure from the fluid pressure motor 20 when the latching member 66 is unlatched. To this end there is secured to the longer dependent arm 61 of the stand 58, as by bolts 78, a valve body 79 having a tapered opening 79a therein. The valve body is further provided with four inwardly extending passages 80 to 83 which terminate in the tapered opening 79a. Rotatably mounted within the tapered opening of the valve body is a tapered valve cock 84 provided with an opening 85 which terminates in a smaller opening 86 of square configuration which receives the extending end of the square shaft 65. Disposed within the opening of the valve cock is a coil spring 87 which is held under compression between a cover plate 88 secured to the valve body and the shoulder 85a formed by the reduced square opening 86 within the valve cock. Suitable gasket means 89 are provided between the valve body and cover and between the valve body and arm 61 of the stand to seal the interior of the valve body against leakage.

The valve cock 84 is formed intermediate its ends with a shallow peripheral groove 84a which registers at all times with the inwardly extending opening 80 in the valve body, the groove 84a being provided to distribute a suitable lubricant injected through the fitting 80a secured in the opening 80. The valve cock 84 is further formed intermediate its ends and approximately diametrically opposite the groove 84a with a second groove 84b, the peripheral extent of the second groove being such to register with the openings 81 and 82 or with the openings 82 and 83 as the valve cock is turned from one extreme position to another. The opening 81 in the valve body 79 is open to atmosphere and the opening 82 is connected via conduit 33 to the valve mechanism 30, while the opening 83 in the valve body is connected through a fitting 98 to a source of fluid pressure. With the latching member 66 in its normal and locked position as illustrated in Fig. 6, the valve cock 84 is in the angular position shown in Fig. 5 in which the fluid pressure opening 83 is connected to the valve body opening 82 through the groove 84b to supply the fluid pressure to the valve mechanism 30. Upon removal of the padlock from the bail 68 of the lever latch stand jaw 59, the foot pedal 67 is depressed to rotate the latching member in a counterclockwise direction (Fig. 5). The lever latch stand jaw is thus uncovered to permit operation of the hand-throw lever 50. The rotation of the latch member also rotates the valve cock 84 in a counterclockwise direction to seal off firstly the pressure supply opening 83 and then interconnect the opening 82 with the opening 81 in the valve body to vent the conduit 33 and valve mechanism 30 to atmosphere.

The lever latch 57 is provided with means for retaining the lever latching member 66 in its unlatched position upon rotation of the hand-throw lever 50 from its normal position toward its reverse position after the latching member has been moved to its unlatched position. To this end there is provided a lock lever 91 pivoted on a pin 92 secured in the end wall of the casing 12. The lever 91 is of modified S-form (Fig. 2) with the end of one arm 91a coacting with the camming member 56 provided on the hand-throw lever hub 51, while the end of the other lever arm 91b coacts with the underside of the foot pedal 67 (Fig. 6). In operating the handthrow lever 59 from its normal position as illustrated in Fig. 2, the cam member 56 in rotating clockwise abuts the end of the lever lock arm 91a to pivot the lock lever 91 in a clockwise direction about the pin 92, thereby bringing the lever lock arm 91b up under the foot pedal .67 to hold the latching member 66 in its unlatched position as long as the hand-throw lever is in any other position than its normal position. The camming member 56 on the hand-throw lever hub 51 extending for approximately of the hub periphery, will hold the lock lever 91 in its rotated position under the foot pedal 67 in all positions of the hand-throw lever except in the normal extreme position within the jaw 59 of the latch stand. Thus the latching member 66 cannot be returned to its latched position either accidentally or by stepping on the return pedal 68 provided on the latching member. As long as the handthrow lever is in any other position excepting its latched position within the jaw 59, the valve cock 84- will be in its shut-off position to vent the valve mechanism 30 of the switch movement to atmosphere.

We 'hewe' lthusprovided an added-safety feature in the operation" oi a fluid pressure operated switch move ment whereby the initialconditioningrof the movement for manual operation by releasing/the latching member locking thehand throw lever in its one extreme position, cuts off the fiuid pressure supply to the movement. A further advantage in the use of our invention is the positive assurance that the fluid'pressure is cut oil? from the switch movement as: long assthe hand-throw lever is unlatched.

Although we have hereinflshown and described only one form of a cut-off valve for afluid pressure operated switch movement embodying our invention,- it is understood that various changes and modifications may :be made therein within= the scope ofxthe appended claims without departing from the spirit and scope of our invention.

Having thus described our invention; what we' claim is:

1. Railway switch operating apparatus comprising,

a member movable to two extreme positions, a fluid pressure motor for moving said member, a hand-throw lever movable between two extreme positions for at times moving saidmovable member, a= latching member movable between a latched position and an unlatched position for latching said 'hand-throw lever in one extreme positioma valvecontrolling theadmission of fluid pressure to said motor, said valve being operatively connected to said latching member, the movement of said latching member to its unlatched position to free said hand-throw lever closing said valve toshut off the fluid pressure supply to said motor, andlock means actuated upon movement of said hand-throw lever from its extreme latched position to hold said latching member in its unlatched position in all positions of the hand-throw lever other than its extreme latched-position.

2. Railway switch operating apparatus comprising, amember movable to two extreme positions, a fluid pressure motor for moving said member, a handthrow lever movable between two extreme positions for at times moving said member, a valve controlling the admission of fluid pressure to saidmotor, a lever latch for locking said hand-throw lever in one extreme position including a latching member movable into and out of the path of movement of said lever, means for locking said'latchingmember in the path of said hand-throw lever only when said lever is in oneof its extreme positions, and means interconnecting said latching member and said valve to close said valve-when saidlatchingmember is moved from its locked position in the path of said hand-throw lever.

31 Railway switch operating apparatus comprising, a member movable to two extreme positions, a fluid pres-' sure motors-for moving said member, a hand-throw lever movable betweentwoiextreme positions for at times moving said =member, a valvecontrolling the admission of fluid pressure to said motor, alever latch for locking said hand-throw :lever inone extreme position including a latching member movable into and-out of the path of movement of said lever, means for locking said latching member inithe path of said hand vthrow'lever only when said lever isin one ofits extreme positions, means interconnecting said latching memberand said valve'to close said valve when said latchingmember is moved from its locked position in the path of saidhand-throw lever, and means operatively connected to said hand-throw lever for holding said latching member outof the path of said lever when said lever is in any position other than said one extreme positiont 4. Railway switch operating apparatus comprising, a member movable to two extreme positions, a fluid pressure: motor for moving said member, ahand-throw lever movable between two extreme positions for at times moving said member, a valve controlling the admission of fluid pressure to said motor, a lever latch for locking said hand-throw lever in one extreme position including a latching member movable into and out of the path of movement of said lever, means for locking said latching member in the path of said hand-throw lever only when said lever is in one of its extreme positions, means for closing said valve upon initiating the release of said latching member from said locked position, and means operatively connected to said hand-throw lever for bolding said latching member out of the'path of said handthrow lever when said lever is in any position other than in said one extreme-position.

5. Railway switch operatingapparatus comprising, a member movable to two extreme positions, a fluid pressure motor for moving said member, a hand-throw lever movable between two extreme positions for moving said member at times, a valve controlling the admission of fluid pressure to said motor, a lever latch including a jaw for receiving the hand-throw lever in one of its extreme positions, a latching member movable from one extreme latched position wherein it overlays said jaw to a second extreme unlatched position wherein the handthrow lever may be moved from said jaw, means for locking said latching member in' its latched position; means for operatively connecting said valve to said latching member whereby said valve is closed when said latching member is moved from its latched position, and means operatively connected with said hand-throw lever for holding said latching memberi'n its unlatched position when said hand-throw lever is out of the jaw of said lever latch.

6; Railway switch operating apparatus comprising, a member movable to two extreme positions, a fluid pressure motor for moving said member, a hand-throw lever movable between two extreme positions for moving said member at times, a valve controlling the admission or fluid pressure to said motor, a lever latch including a jaw for receiving the hand-throw lever in one of its extreme positions, a latching member movable from one extreme latched position wherein it overlays said jaw to a second extreme uniatcned position wherein the nanothrow lever may be moved from said aw, means ror locking said latching member in its latched position; means for operatively connecting said valve to said latching member whereby said valve is closed when said latching member is moved from its latched position, a locking lever movable into the return path of said latching member to its latched position, and camming means on said hand-throw lever for moving said lockinglever into the return path of said latching member when said handthrow lever is out of the jaw of the lever latch.

References Cited inthe file of this patent UNITED STATES PATENTS 1,791,799 Coleman Feb. 10, 1931 1,833,679 Jefferson et al Nov. 24, 1931 2,092,828 Bone Sept. 1-4, 1937 2,649,537 Smith Aug. 18, 1953 

